Metal forming machine



April 14, 1942. BERUNER 2 2,279,964

METAL FORMING MACHINE Filed Oct. '7, 1938 2 Sheets-Sheet l 1 INVENTOR. v HENRY f2 BE/iL/NER ATTORNEYS.

' H. A. BERLINER METAL FORMING MACHINE April 14, 1942.

2 Sheets-Sheet 2 7 Filed Oct. 7, 1.938

INVENTOR. #Emm BERL/NER A TTORNEKS.

I Patented Apr. 14, 1942 UNITED STAT 'aziaeai METAL'FORMING MACHINE Henry A. Berliner, Washington, D. 0., assigne: ts, to Engineering and Re- Riverdale, Md., a corporaby mesne assignmen search Corporation, tion of Maryland Application October 7, 1938, Serial No. 233,726

2 Claims.

This invention relates to metal forming machines and more particularly to improved work holding clamps and operating means therefor.

One of the objects is to provide a metal forming mac.;ine having a work holding clamp which will hold the work securely. According to one important feature the strain on the work tends to tighten the clamp so that the work will be 'held tighter as the strain increases. p

Another object ofthe invention is to provide a metal working machine having a work holding clamp which may be operated by fluid pressure. The fluid pressure preferably gives the clamp an initial set and further tightening is effected by strain on the work piece itself.

Still another object of the invention is to provide a metal working machine having a plurality of adjustably mounted clamps to accommodate work pieces of different shapes. According to one feature of the invention the clamps are operated by fluid pressure supplied through flexible connections and controllable to operate the clamps separately or simultaneously.

Other objects, advantages and novel features of the invention will be apparent from the following description of the accompanying drawings, in which:

Figure l is a partial side elevation of' a machine embodying the invention;

Figure 2 is a partial end view showing the clamps;

Figure 3 is'an enlarged front view of a clamp;

Figure 4 is a section onthe line 4-4 of Figure 3; and

Figure 5 is a partialsection on the line of Figure 4.

The invention isillustrated in a machine for forming sheet metal into irregular shapes, as for example to form parts for aircraft or the like. As best seen in Figure 1 a base l0 supports a pair of elongated support beams l2 extending transversely of the base and adjustable longitudinally thereof. A plurality of clamps H are mounted on each ofthe beams ends of a metal sheet l6.

Between the beams I2 there is arranged a vertically movable hydraulic piston I8 having a platform 20 removably securedto its upper end. A male form 22 which may be made of wood or other suitable material is mounted on theplatform 20 in a position to engage the sheet Ili.

While the form 2'2 shown in Figure l is of a. 7

very simple shape it will be understood that forms of any desired shape or size can be employed.

In use the metal sheet I6 is clamped in the i2 and grip the "opposite clamps l4 and pressure is applied to the piston l8'to raise it. pressed up into the sheet, causing the sheet to be stretchedand bent into the shape of the form. In order to secure the clamps M to the beams I2, the beams are formed with central slots 24 (Figure 4) and bolts 26 having enlarged lower ends 28 are extended through the slots and through suitable bosses 30 on the clamps. The ends 28 engage the sides of slots 24 and nuts 32 are provided to draw the clamps rigidly against the beams l2. clamps can be adjusted to any desired position on the beams to accommodate a work-piece of irregular edge outline and to assist in this adjustment screws 34 are provided in the clamps engaging flanges 36 on the beams.

At its upper end each of the is formed with an outwardly converging elongated slot. The converging side walls of the slot are preferably faced with hard metal bearing strips 38 serving as one bearing surface for antifriction rollers 42. Guard strips 48 are preferably provided at the top of the slots to keep dirt chips and the like from falling into the rollers 42. A pair of elongated tapered clamp jaws M is mounted in each slot with one surface engaging the rollers 62 and the inner facing surfaces substantially parallel to receive a work piece between them. Preferably the inner surfaces are roughened to grip a work piece more securely.

' End plates 45 on the clamp body It serve to prevent endwise movement of the jaws in the slots. plates 49 holding them out the top. a s

According to one important feature of the invention the inner clamping surfaces of the jaws are not exactly parallel but'diverge outwardly very slightly. Thus a strip clamped in the jaws is clamped hardest at its inner edge with the clamping force progressively decreasing toward the outer edge of the paws. Thls avoids stress concentration in the strip at the outer edges of the jaws and eliminates/ the tendency of the sheet to tear at this point.

One desirable manner of obtaining this result j is to proportion the jaws and. the body so that of the jaws. the outer portion this gives the desired action,

- the body being stiff enough to give a gripping acnon throughout the major portion of the Jaw area. I I The jaws 44 are operated by pistons mount- This causes the form 22 to be By loosening the nuts 32 the clamp bodies M against coming 'desired.

When fluid pressure is supplied to a clamp the ed in cylinders 48 in the body and connected at their lower ends to fluid passages 50. Preferably two or more spaced cylinders and pistons are provided in each clamp to operate the elongated clamp jaws uniformly throughout their length. Bores 52 are provided in the clamp bodies terminating in nipples 5| to conduct operating fluid into the passages 50.

Compressed -air or other suitable operating fluid is supplied to the clamps through a manifold pipe 56 connected to a suitable source of fluid through a master valve 58; Aplurality of spaced nipples controlled by individual control valves 60 are provided in the manifold 56 connected to the nipples 54 through flexible conduits 62.

This arrangement makes it possible to operate all or any selected group of the clamps simultaneously or to operate the clamps individually. For the first mode of operation all or a selected group of the valves 50 may be opened and their the master valve 58 may be opened to supply fluid simultaneously to allof the clamps whose valves 60 are Open. To operate the clamps individually the master valve 58 may be opened and the valves 60 may then be opened separately as pistons 45 will be moved upwardlyto move the jaws upwardly in the slots. As the jaws move they will be cammed together to grip a work piece tightly between them and as tension is ap-' plied to the work piece it will tend to pull the jaws still farther out so that'they will be cammed still tighter together. Thus the greater the tension applied on'the work piece thetighter the jaws will grip it. When the tension is removed and the fluid pressure is relieved the laws will drop down to release the .work piece so that it can easily be removed.

The pistons 46 need not be extremely power ful but should exert enough force so that the jaws will straighten'out any small waves or kinks in the edge of a sheet metal work piece. In this way the jaws bear on the work piece throughout their fulllength and provide a flrm initial grip so that the piece will not slip when tension is applied as might happen if the jaws bore on only one or two high spots.

While the invention has been described and illustrated in connection with a particular metal erence will therefore be had to the appended claims for a determination of the scope of the invention.

What is claimed is: I

1. In a sheet metal forming machine of the type in which the opposite edges of a sheet are clamped to spaced straight beams and the sheet is subjected to a stretching operation between the beams, means for clamping each edge of a sheet to a beam comprising a plurality of identical clamp devices adjustably mounted side by side along the length of each beam, each of said clamp devices comprising a body having an upper surface, a recess extending through the body which is of substantially uniform transverse cross-section with the longitudinal axis of the recess substantially parallel to the beam and which has side walls which converge toward the upper surface of the body to define an elongated opening in the upper surface for the recess, a pair of clamping jaws within said recess which are of approximately the same length as the recess and are of substantially uniform cross-sec-' tion throughout their lengths, each of said jaws having an outer inclined face adjacent and parallel to one of the converging walls of the recess and said jaws having inner adjacent faces substantially parallel to each other between which the edge of a sheet of metalis adapted to be placed-and fluid pressure means disposed within the body of each clamp for moving the clamp- .ing jaws toward the opening for the recess whereby the converging walls of the recess force the jaws toward each other to clamp the edge of the sheet of metal therebetween, the inclined faces of the jaw members and the converging walls of the recess being so disposed with respect to each other that during movement of the jaw members toward the opening for the recess the inner faces of the jaw members remain substantially parallel, and hydraulic control means whereby the jaw-moving means of all of the clamping devices may be operated simultaneously and to the same extent.

2. A clamping device according to claim 1, in whichthe means for moving the clamping jaws comprises a cylinder arranged within the body of-the clamping device below the bottom of the recess therein, a piston disposed within the cylinder and one end of which engages the lower faces of the jaw members, and means for introformingmachine it will be understood that it ducing fluid under pressure into the cylinder to cause movement of the piston and the jaw members toward the opening of the recess. HENRY A. BERLINER. 

